Re: inhibit compiler warning C4624 for a class hierarchy


"Charles Wang[MSFT]" <changliw@xxxxxxxxxxxxxxxxxxxx> wrote in message
news:lJdfiAAOHHA.2080@xxxxxxxxxxxxxxxxxxxxxxxxx
Hi rbv,
The undefined behavior means that the behavior is decided by the compiler.
Different compilers may cause different behaviors. C++ standard does not
define a consistent behavior for this situation.

For your four requirements, I am afraid that it is hard to implement
unless
you do some changes. Even if you use template allocator/deallocator, your
none-virtual Destroy method is defined in your base class OpNotification
and it uses "delete this". This only release your base instance space,

I would change that call to invoke the deallocator.

however if your derived class instance includes additional data members,
this may cause memory leak due to some left spaces not released.

No allocator I'm aware of ever frees less than the entire block. Leaks
could appear due to member destructors not being called, for this reason
this hierarchy will permit only POD members.

Since my template allocator/deallocator would invoke (new BYTE[] / delete
[]), it's guaranteed to free the entire block originally allocated, even
though the deallocator didn't know the original type. I'd lose member
initializers.... well, I could invoke a member function through the template
typename argument to initialize the buffer, ala two-step construction. What
I lose is the ability to for each buffer initializer to define a set of
mandatory arguments. I guess I can make the two-step initialization
explicit.

Then there wouldn't be any mismatch between constructor and destructor
calls, because neither would be called. The dynamic type of every object
would be BYTE[]. Compiler behavior would be well defined by the standard.

The really nice thing with constructors, though, is the way they aren't
implicitly inherited.

What I ultimately want is a family of structures sharing a common header so
that they can be used polymorphically, with a convenient initialization
syntax. Multi-level (not multiple) "inheritance" is a plus, but not needed
at the moment. Just like the ENHMETARECORD family of structures, but not as
ugly.


Why do not you use a macro for releasing your object? It might be the
least
work in your situation.
For example:
#define __ReleaseB(pB) \
delete pB;\
pB=NULL;

That really doesn't solve any problems. I need to be able to
polymorphically destroy the request objects if I encounter an error
condition, such as the port being closed.


Hope this helps! Please feel free to let us know if you have any other
questions or concerns.

Thanks for all your help with this. Getting this done right is really going
to help future maintainability.


Sincerely yours,
Charles Wang
Microsoft Online Community Support

======================================================
When responding to posts, please "Reply to Group" via your newsreader
so that others may learn and benefit from this issue.
======================================================
This posting is provided "AS IS" with no warranties, and confers no
rights.
======================================================













.

Relevant Pages

  • Re: Uninitialized variables
    ... > unintialized variables to zero on the old CVF forum, ... > eems reals and integers have a default initialization of the largest ... The Fortran compiler no longer "owns" the linker/OS ... all of the time and the standard doesn't ...
    (comp.lang.fortran)
  • Re: Component Initialization of Module Variables
    ... who does not worry about how the compiler would go about ... from the standard and from textbooks, leaving just the error message as ... has "component initialization", which isn't a term used in the standard, ...
    (comp.lang.fortran)
  • Re: initializing static class variables
    ... >> I believe it was introduced in 2003 standard but I can't be sure since I ... >> default constructor is called. ... the definition of compiler generated default constructor. ... constructed with default initialization. ...
    (comp.lang.cpp)
  • Re: Component Initialization of Module Variables
    ... there should be no default initialization, ... I didn't go back and check the standard to make sure all was ... initialization would not apply to allocatables in any case. ... who does not worry about how the compiler would go about ...
    (comp.lang.fortran)
  • Re: help me learn C
    ... I have been on here over 14 years but a member of the ISO C panel for ... If you want to discuss ISO C there is Comp.std.c ... OS or a compiler etc there are specific groups for that. ... that is only used in the standard, but virtually no where else, to ...
    (comp.lang.c)